Various systems and applications transport encoded speech over communication networks. Speech coding is used, for example, in Voice over Internet Protocol (VoIP) systems. Speech coding is specified in a number of communication protocols, such as in the Real-time Transport Protocol (RTP). RTP is described, for example, by Schulzrinne et al., in “RTP: A Transport Protocol for Real-Time Applications,” Request For Comments (RFC) 3550 of the Internet Engineering Task Force (IETF), July, 2003, which is incorporated herein by reference.